Department of Agroenvironmental Sciences and Technology, University of Bologna, I-40127 Bologna, Italy.
J Exp Bot. 2011 Jan;62(2):409-38. doi: 10.1093/jxb/erq287. Epub 2010 Nov 1.
Association mapping was used to dissect the genetic basis of drought-adaptive traits and grain yield (GY) in a collection of 189 elite durum wheat accessions evaluated in 15 environments highly different for water availability during the crop cycle (from 146 to 711 mm) and GY (from 9.9 to 67.3 q ha(-1)). For highly heritable traits (e.g. heading date, kernel weight, etc.) several significant experiment-wise marker-trait associations were detected across five or more (up to 13 for kernel weight) environments, with R(2) values ranging from ca. 5 to 10%. As to GY, significant associations (R(2) from 2.5 to 4.2%) were mostly detected in one environment only (56 markers), while decreasing rapidly from two to five environments (from 20 to three markers, respectively) and with only one marker (Xbarc197 on chr. 5A) found significant in six environments (ranging from low- to high-yielding). These results are probably due to the complex genetic basis of GY and its interaction with environmental conditions. The number of markers significantly affecting GY decreased considerably under drought conditions, suggesting a limited effectiveness of association mapping to identify loci for GY under low-moisture conditions, most likely because different genotypes can attain similar phenotypes via different morpho-physiological traits and corresponding gene networks. Our study confirmed the role of major loci for phenology previously described in biparental mapping populations, highlighted a novel set of loci for drought-adaptive traits, and provided information on the agronomic value of the alleles at such loci across a broad range of soil moisture conditions.
关联分析被用于剖析 189 份硬粒小麦优良品种在 15 个环境中的遗传基础，这些环境在作物周期内的水分可用性（从 146 到 711 毫米）和产量（从 9.9 到 67.3 q ha(-1)）方面差异很大。对于高度遗传的性状（如抽穗期、千粒重等），在五个或更多个环境中（最多有 13 个环境用于检测千粒重）检测到了几个显著的实验性标记-性状关联，R(2) 值在 5%到 10%左右。至于产量，只有一个环境（56 个标记）检测到显著的关联（R(2)值从 2.5 到 4.2%），从两个到五个环境（从 20 到 3 个标记，分别）的关联数迅速减少，只有一个标记（Xbarc197 在 5A 染色体上）在六个环境中显著（从低到高产量）。这些结果可能是由于产量的遗传基础复杂，以及其与环境条件的相互作用。在干旱条件下，显著影响产量的标记数量大大减少，这表明关联分析在低水分条件下识别产量基因座的效果有限，这很可能是因为不同的基因型可以通过不同的形态生理特征和相应的基因网络达到相似的表型。我们的研究证实了先前在双亲和图谱群体中描述的主要性状位点的作用，突出了一组新的与抗旱性状相关的位点，并提供了这些位点的等位基因在广泛的土壤水分条件下的农艺价值信息。
